(1) Field of the Invention
This invention concerns a machine and methods of repairing railway tracks and, in particular to replacement of a type of crossbeam for railway tracks termed half ties. The invention is particularly related to methods for the extraction or removal of the half ties.
(2) Description of the Art
Common railway track includes two parallel, spaced rails, normally made of iron or steel. The rails are secured to crossbeams, referred to as railway or railroad ties, or sleepers. The ties are typically timber, but concrete or steel ties are also known. Each of the ties individually spans the distance between the two rails and functions to support the rails and maintain the rails at a predefined distance apart. The ties are typically laid on a foundation including a bed of ballast or secured to solid concrete, for example.
Some railway track systems, notably some subway systems, construct the railway somewhat differently. The railway foundation is a pair of parallel concrete ridges, separated by a trough that functions to drain water from the track area. Each of the concrete ridges includes a number of half ties disposed within vaults formed in the concrete ridges. A rail is attached to the half ties on each of the concrete ridges.
It is commonly known that maintenance of railway track includes periodic replacement of damaged, worn or otherwise unsuitable railway elements, and frequently involves the replacement of wooden ties. This is also true for subway systems, where water is frequently present, causing water damage to elements of the railway.
It is a common technique, with respect to conventional railway tracks, to use complex machinery to replace ties in an automated fashion and perform other track maintenance. The machinery that performs these tasks belongs to a class of equipment call “Maintenance Of Way” or MOW equipment. These machines perform many different functions, all related to keeping the track system in good order. They are capable of continuous processes, including changing out the ties, “cleaning” or replacing the railroad ballast, adjusting the track gage (distance between the rails), installing rail clips (the things that attach the rails to the ties), grinding the rail head to a very precise shape, measuring the contour of the rail head with lasers, and many more jobs. They can even continuously replace the rails and ties while riding on the rails they are replacing. The particular machine used to replace ties is a “tie inserter.” The tie is unfastened from the rail, the ballast is cleared from around the tie, the machine grabs the old tie at the end, pulls it out to the side, then inserts a new tie and repeats the whole process in reverse order, and then it moves to the next tie and does it again.
Currently, however, there is no efficient method of replacing subway half ties. This is due, at least in part, to the fact that the ties are enclosed, at least partially, in a vault. Thus, typically, half ties are removed by hand with a hand held jackhammer. The operator uses the jackhammer to reduce the half tie into small pieces. The pieces are then removed with a shovel or similar device. In the alternate, a larger piece of equipment, such as a hydraulic hammer, is used to chop the half ties into small enough pieces to permit removal by shovel or the like. A problem with this approach is the time it requires to chop up the ties and then remove the pieces, not to mention the need for several persons manually performing the required tasks.
There is a need for an efficient and effective device and method of replacing half ties. The invention satisfies the need.